/*  Copyright (c) 2000-2006 hamcrest.org
 */
package org.hamcrest.core;

import static org.hamcrest.core.IsNot.not;

import org.hamcrest.BaseMatcher;
import org.hamcrest.Description;
import org.hamcrest.Factory;
import org.hamcrest.Matcher;

/**
 * Is the value null?
 */
public class IsNull<T> extends BaseMatcher<T> {
	@Override
	public boolean matches(Object o) {
		return o == null;
	}

	@Override
	public void describeTo(Description description) {
		description.appendText("null");
	}

	/**
	 * Matches if value is null.
	 */
	@Factory
	public static <T> Matcher<T> nullValue() {
		return new IsNull<T>();
	}

	/**
	 * Matches if value is not null.
	 */
	@Factory
	public static <T> Matcher<T> notNullValue() {
		return not(IsNull.<T> nullValue());
	}

	/**
	 * Matches if value is null. With type inference.
	 */
	@Factory
	public static <T> Matcher<T> nullValue(@SuppressWarnings("unused") Class<T> type) {
		return nullValue();
	}

	/**
	 * Matches if value is not null. With type inference.
	 */
	@Factory
	public static <T> Matcher<T> notNullValue(@SuppressWarnings("unused") Class<T> type) {
		return notNullValue();
	}
}
